Write an Android application

Hi i want to develop lightweight application for android that receive the broadcast messages received from the another application. Say i have some 200 groups (similar to whats app),so user will choose this of groups he is interested. So say "User1" subscribed to Group1,G2,G10,G20". (4 groups) User2 subscribed to " G1,G10,G50,G200" So i send some data (pic or text) to that G50 group,it should be received on User2 mobile and if data sent to G1 then it should be received on both user 1 and user2 mobile. Subject or title of msg should be the group name and msg received on same group name should be clubbed together Should be displayed in order based on time,Latest msg on top. App should be oneway communication from server to client. Client should be able to join the group based the database in website,no request need for client to join each group. Should work on all models and versions of android phone. Should instantly deliver the msg from server,like whatsup Ringtone can be changable and background color also should be dynamic to change